1. Field of the Invention
The present invention relates to an image reading apparatus which reads an original and converts image information of the original into digital image signals.
2. Description of the Prior Art
An original reading apparatus is conventionally used as an image input device for a digital copying machine or the like. This apparatus uses an image sensor such as a CCD for reading image information of an original and converts the read image information into digital signals. In an apparatus of this type, an image of the original must be formed at a predetermined position on the image sensor by moving the mounting position of the image sensor such as a CCD or the position of the optical system mirror or lens.
When such an adjustment is made, a loupe or the like is used to observe the CCD from the position of the original surface so as to correctly adjust the mounting positions of the mirror, lens and CCD. This adjustment operation has poor workability, is time-consuming, and costly. When readjustment must be effected after installation of the apparatus at a user's office or the like, the serviceability is impaired.